Field of the Invention
Exemplary embodiments of the present invention relate to a multistage fiber filtering apparatus and, more particularly, to a multistage fiber filtering apparatus capable of selectively filtering depending on turbidity of raw water.
Description of the Related Art
In general, a filtering apparatus which filters contaminated raw water by using a filter to make the contaminated raw water clean treated water and supply it has been widely used not only for drinking water but also for treatment of water and sewage or factory water. In particular, the filtering apparatus used for treatment of river water or factory wastewater or seawater desalination facilities is becoming larger and larger in order to increase the water quantity to be treated and improve water quality.
There is a multi type filtering apparatus that is used for the large-capacity water treatment applications. For example, Korean Patent No. 10-0438460 entitled “Multi type air gap controlling fiber filter” can be referred for teaching such.
In addition, as a method used in existing water purification plants, water treatment plants, or seawater desalination plants, there is a method for filtering water produced from the filter again using a cartridge filter separately installed, which requires a lot of installation sites and costs. In summary, in the above case, there is a problem in that the occupied space or the installation space becomes very large and thus a lot of site is required or cost is increased.
Accordingly, in order to improve the treating speed and improve the water quality, a plurality of filters are used or a plurality of stages (multi stages) are arranged in the same filtration tank. For example, Korean Patent No. 10-0898122 entitled ‘Vertical multistage link type pore control fiber filter’ is disclosed.
In the existing vertical multistage link type pore control fiber filter, if an air gap controlling fiber filter medium is formed in a filtration tank around a strainer so that raw water in the filtration tank passes through the fiber filter medium to be introduced into the strainer, a plurality of unit fiber filters draining the raw water to a lower end of the strainer are vertically stacked by making lower ends of the strainer of the respective unit fiber filters communicate with upper ends of the filtration tank of the respective lower unit fiber filters, the filtration tank of an uppermost unit fiber filter is provided with a raw water inlet through which external raw water is introduced, and the lower end of the strainer of a lowermost unit fiber filter communicates with a filtered water discharge pipe to drain filtered water to an external water tank.
At this time, the vertical multistage link type pore control fiber filter has a structure in which the raw water is introduced through the raw water inlet pipe 11 formed at an uppermost end of a filtration tank 10, passes through all multistage fiber media 20, and then is discharged through a filtered water discharge pipe 12 formed at a lowermost end of the filtration tank 10.
However, the quality of the raw water to be treated is variable. In particular, the fluctuation in the quality of the raw water is very large during summer and rainfall, and therefore the raw water cannot but unnecessarily pass through all the fiber media even if the raw water need not be subjected to the multistage filtration all the time.